The present invention relates to switching devices, and more particularly to an improved structure of sliding block electrical switch which eliminates the drawbacks of the sliding block electrical switch of U.S. Pat. No. 5,153,401, which is also an invention of the present inventor.
The sliding block electrical switch according to U.S. Pat. No. 5,153,401, as shown in FIG. 1, which comprises a base 1, which has a rectangular slot 12, depressions 13 located by each of two long sides of the rectangular slot 12 and respectively separated by walls 131, and holes 16, contact metal pieces 15 respectively lodged in the depressions 13, a sliding block 2, which has a protruded portion 21 and a clamping block 22, two short circuit metal pieces 23 received in the rectangular slot 12 and respectively retained between the protruded portion 21 and the clamping block 22 of the sliding block 2 and moved by the sliding block 2 to make contact with the contact metal pieces 15 adjacent to each other, and a cover 3, which has hooks 31;32 respectively hooked in holes 16 on the base 1. This structure of sliding block electrical switch is easy to assemble and disassemble manually without the use of any tools or fastening elements. As shown in FIG. 2, the sliding block 2 is capable of moving in the rectangular slot 12 so as to trigger the short circuit metal pieces 23 to make contact with the contact metal pieces 15 located at different positions in order to carry out the function of circuit switching. In order to let the sliding block 2 be moved in the rectangular slot 12, the width of the sliding block 2 must be narrower than the width of the rectangular slot 12. This limitation affects the stability of the sliding of the sliding block 2 in the rectangular slot 12. Because there is no positioning means to hold the sliding block 2 in the rectangular slot 12 and the contact between the short circuit metal pieces 23 and the contact metal pieces 15 is a contact between plains and circular surfaces, a contact error may occur easily.